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Discussion Starter · #1 ·
I am getting ready to install my new electric fan and wish to fuse the circuit to prevent a repeat of my previous post: http://www.trifive.com/forums/showthread.php?t=110270&highlight=Electric+fan+saga
Which in-line fuse holder would you suggest? The factory calls for a 40 amp fuse, but the wires coming out of the fan motor sure aren't rated for 40 amps. They're like #16 gauge. After searching Radio Shack and several auto parts houses, the highest fuse/fuse holder I can find is rated for 30 amps. And the wire for some of those is #12 gauge. I know the max current draw is during start-up or if there is a short in the motor or if the blades are blocked:sad0049:. Would a 30 amp fuse blow every time the fan starts up? Any help would be appreciated.
 

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I've had so much trouble with blade type of fuse holders they sell at the local auto parts stores, I won't use them anymore.

For higher amperage, I like the MIDI/AMI fuses and holders.

I buy that kind of stuff from Waytek.
http://www.waytekwire.com/products/1495/Fuse-Holders/&Fuse-Type=MIDI--AMI-fuses

I also don't use crimp-on insulated terminals. I buy uninsulated ones and crimp, solder and cover with adhesive lined heat shrink. I get it all from Waytek.
 

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How is the fan wired now? Where is the relay? How do you control the fan? Where are you getting power to the fan from?
 

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Discussion Starter · #4 ·
How is the fan wired now? Where is the relay? How do you control the fan? Where are you getting power to the fan from?
At the moment my car is 250 miles away from me so I cannot double check my answers, but I am 99.9% sure I am correct.
I do know that the fan is connected to two relays. One is energized when the +12 volt supply is going to the A/C compressor, thus causing the fan to kick on when the compressor does. (I’m not particularly happy with this set up, but……….). The second relay is connected to a thermostat set to energize at 1800. And I know that the +12 volts for the fan from both of those relays is coming directly from the battery. The relays are mounted on the inside of the panel of the driver’s side radiator support.
Interestingly, only the wires belonging to the fan itself overheated. I had solid (or so I thought) mechanical connections between the two factory “fan wires” and the wires from the relays, yet none of the wires the between the mechanical connections and the relays showed signs of overheating. However, the mechanical connections themselves did get warm enough to begin melting the insulation and electrical tape around the connections.
 

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Trifive Automotive Electrical Wiring Expert
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And I know that the +12 volts for the fan from both of those relays is coming directly from the battery. The relays are mounted on the inside of the panel of the driver’s side radiator support.
Interestingly, only the wires belonging to the fan itself overheated.

It does sound like you need a smaller fuse between the battery and the relays. The fan wires apparently aren't big enough to carry 40 amps. I think 30 amp fuses would be OK, because of the very short time the fan draws higher current.
 

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At 30 amps, that means you can go with an ATO or Maxi fuse. But, I don't like holders for them.

For dependability, I think the MIDI/ANL fuses and holders are the way to go.
 

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Discussion Starter · #7 · (Edited)
It does sound like you need a smaller fuse between the battery and the relays. The fan wires apparently aren't big enough to carry 40 amps. I think 30 amp fuses would be OK, because of the very short time the fan draws higher current.
Don - would you agree that putting the fuse in line (series) with the fan lead will accomplish the same thing? To my way of thinking, the relays should be in parallel with each other but both would be in series with the fan motor.
 

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For 30 and 40 amp applications I use circuit breakers. Roger turned me on to Waytek also, and for automotive electrics they are a full service supplier.
http://www.nxtbook.com/nxtbooks/waytek/catalog226/#/131/OnePage
:anim_25:
FWIW,
My thinking about breakers is that I'd rather blow a fuse if there is a problem somewhere. When I see a blown fuse, I know I have a problem. If a breaker intermittently breaks and automatically resets, it could make it more confusing to find the issue. Also, my Vintage Air system came with a breaker and I switched it out to a fuse.
This is strictly a personal choice of mine. A properly working breaker will be perfectly safe. Could get you home if it did break and reset iterations where it wouldn't with a fuse I guess.
Don't all OEM's all use fuses? To my knowledge they do. I guess if I were to use a breaker, I would prefer one that didn't automatically reset.

Randy57 has a thread going now and has had problems with using a 30A breaker and he just switched to a 40A. Could have been a defective breaker though.

http://www.trifive.com/forums/showthread.php?t=109253&goto=newpost
 
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